This invention relates to a recording material for forming color images by using hot-melt inks each comprising a coloring material and a thermosetting resin, and a method for forming color images by using such recording material.
Silver salt photographic system, which is excellent in resolving power, and non-silver salt photographic system, which includes electrostatic recording system and electrophotographic system, are known as color image forming methods. Non-silver salt system is inferior to silver salt system in color image quality, but as it enables reproduction of tones, this system is used for copying of color images, etc.
These systems, however, are complicated in the process for obtaining color images, so that their equipments are large in size and fine maintenance is required therefor, making these systems costly.
Recently, with the development of computers, request has been voiced for enabling reproduction of color images formed on CRT, etc., as "hard copies" so that one can see them by taking them up on his hand. For realizing this, several methods have been proposed in which color images are formed after converting the images into electric signal. In these methods, heat transfer system and ink jet system are most typical. In the former system, at least one coloring material is transferred to image receiving paper from transfer paper applied with plural coloring materials by using thermal head. This system enables a reduction in size of the apparatus and also makes it maintenance-free, but the image sharpness is poor since the image resolving power is decided by the size of the heat generating section of the thermal head. Also, this heat transfer system is subject to certain limitation on speed-up of recording as it is necessary to use transfer paper coated with coloring materials of at least three colors, viz. yellow, magenta and cyan, when forming a color image. It is another drawback to this system that the three color layers are consumed even when forming a single-color or 2-color image.
According to the ink jet system, images are formed on image receiving paper by spurting inks from the respective nozzles, so that this system has the problem that the nozzles might be choked up with ink. Also, as it is necessary to spurt inks of different colors from the respective nozzles for forming color images, there are required at least three nozzles.
On the other hand, Japanese Patent Unexamined Publication No. 59-230786 discloses a recording material which can provide a color image easily. According to this Japanese Publication, there is formed on image (or picture) elements a white opaque layer, which is then removed from necessary image element portions to give a color image. But this technique is disadvantageous in that the use of adhesive tape is necessary to remove the white opaque layer and resolving power is insufficient.
Therefore, there have been desired for an easier process for forming maintenance-free color images and color image recording materials used therefor.